Al-Mustansir Billah

al-Mustansir Billah (5 July 1029-10 January 1094) was the Caliph of the Fatimid Caliphate from 1036 to 1094, succeeding Ali az-Zahir and preceding Ahmad al-Musta'li. His reign of 58 years was the longest reign of any Caliph.

Biography
Hibatullah ibn Musa Abu Nasr was born on 5 July 1029 in Cairo, Egypt, in the Fatimid Caliphate to a Shi'ite Muslim family. Upon the death of his father, Caliph Ali az-Zahir, al-Mustansir Billah succeeded him as the Caliph of the Fatimid Caliphate, becoming the spiritual leader of Shia Islam. Al-Mustansir presided over the Fatimid Caliphate for 58 years, and under his rule Turkish and Sudanese mercenaries in his army fought each other, and the Turks were victorious in the end. al-Mustansir also fought the rebels in Dongola in the Upper Nile, in addition to the rebellious warlords of North Africa. He died in 1094, and he was succeeded by Ahmad al-Musta'li as Caliph.